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Title: Characterisation of metallic nanoparticles in aqueous solutions and organic solvents
Author: Nwoko, Kenneth Chinedu
ISNI:       0000 0004 7967 6862
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2019
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The aim of this study was the characterisation of metallic NPs in aqueous and organic solvents using asymmetric flow field-flow fractionation (AF4) simultaneously coupled with ultraviolet visible spectroscopy (UV-VIS), multi-angle light scattering (MALS), and inductively coupled plasma mass spectrometry/mass spectrometry (ICP-MS/MS); combined with other complementary techniques. Sample matrix effects on the particle size and integrity of iron (Fe) oxide nanoparticles (IONPs) was investigated by spiking them into rat blood cells and plasma fractions. MALS suggested polydispersity in both fractions, indicating size modification of IONPS. Single particle mode ICP-MS (spICP-MS) yielded monodisperse pristine IONPs and IONPS spiked into blood cells; while IONPs spiked in rat plasma were polydisperse. Elemental Se/Te NPs biosynthesised from a fungi Aureobasidium pullulans grown in a nutrient media amended with Na2SeO3/Na2TeO3 were fractionated and characterised. Effect of carrier solutions on particle size was investigated using an aqueous surfactant (Novachem, NVC), and phosphate buffer (PB). Gold nanoparticles (Au-NPs) in an alcoholic liqueur were investigated using dynamic light scattering a (DLS) and spICP-MS; with spICP-MS yielding a median particle diameter of 52.3 ± 0.4 nm and particle number concentration of 3.5 x 107 Au particles/L. Surface functionalised AuNPs with linkers for antibody and radionuclide conjugation intended for therapeutic applications were characterised. Particle sizes were determined with external size calibration with ICP-MS and UV-VIS; with UV-VIS showing better sensitivity than MALS because of surface plasmonic effect. The novel application of AF4-UV-MALS-ICP-MS for separation of metal containing NPs in a gas condensate was reported. AF4-MALS-ICP-MS/MS confirmed the presence of Hg, Fe, Pb, Al, As, Ti, in the MALS peak, which was corroborated with scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDX). This study has demonstrated a complementary application of diverse analytical techniques for the detailed characterisation of metallic NPs dispersed in aqueous solutions and organic solvents.
Supervisor: Feldmann, Jörg ; Krupp, Eva M. Sponsor: Niger Delta Development Commission (NDDC) ; Nigeria
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Nanoparticles ; Metal clusters ; Light ; Mass spectrometry ; Solvents